The following description, often references on an oil filter and an application thereof in a motor vehicle, which it is of course clear that liquid filter according to the invention can also be used for filtering other liquids, such as for example fuel, so that the following remarks also apply in an analogous way to liquid filter and in particular to fuel filter. That means, that despite the description relates to an oil filter module, liquid filter module according to the invention is not limited thereto.
As widely well-known, when an engine is driven, liquid, particularly oil, may be supplied to each of friction portions within the engine to perform smooth lubrication and cooling at the friction portions. The liquid, particularly the oil, may be contaminated by various foreign substances such as metal particles, carbon particles, and oxides generated when the liquid, particularly the oil, is oxidized in proportion to an operation time of the engine. If the operation of the engine is continuous in the state in which the liquid, particularly the oil, is contaminated, the friction rotating portions such as a crankshaft and a cylinder may be gradually worn out and thus be damaged. When the abrasion becomes worse, the friction rotating portions may burn to cause the risk of accidents.
As described above, the maintenance of clean liquid, particularly oil, is very important because of being directly related to a lifecycle and performance of the engine. An oil filter module for example must be essentially installed in an oil circulating system of the engine, and the oil has to be maintained in the clean state.
After a predetermined period is elapsed, the used engine liquid, particularly the oil or the fuel, has to be drained, and then new oil has to be poured in. In case of the liquid filter module, particularly oil or the fuel filter module according to the related art, a method in which a drain bolt screw-coupled to a lower portion of the liquid filter module, particularly the oil or the fuel filter module is removed has been used as a method for draining the engine liquid, particularly the oil or the fuel. However, when the drain bolt for draining the engine liquid, particularly the oil or the the fuel, is screw-coupled to a drain hole, like the liquid filter module, particularly the oil or the fuel filter module according to the related art, since the inner liquid, particularly the oil or the fuel, flows down while the drain bolt is separated, the drain bolt, work tools, and worker's hands may be stained with the engine oil and thus contaminated. Also, in this process, the oil may be spattered on the workplace to contaminate the surroundings.